Provision Of Perches Research Articles

Impact of Perch Provision Timing on Activity and Musculoskeletal Health of Laying Hens.

Laying hens can experience a progressive increase in bone fragility due to the ongoing mobilization of calcium from bones for eggshell formation. Over time, this escalates their susceptibility to bone fracture, which can reduce their mobility and cause pain. The provision of perches as an exercise opportunity could potentially enhance bone strength, but the timing of exposure to perches during the birds' development may modulate its impact. The objective of this study was to investigate the enduring impacts of perch provision timing on the musculoskeletal health of laying hens. A total of 812 pullets were kept in different housing conditions (seven pens/treatment, 29 birds/pen) with either continuous access to multi-tier perches from 0 to 40 weeks of age (CP), no access to perches (NP), early access to perches during the rearing phase from 0 to 17 weeks of age (EP), or solely during the laying phase from 17 to 40 weeks of age (LP). At weeks 24, 36, and 40 of age (n = 84 birds/week), three birds per pen were monitored for individual activity level, and blood samples were collected from a separate set of three birds per pen to analyze serum levels of tartrate-resistant acid phosphatase 5b (TRACP-5b) and C-terminal telopeptide of type I collagen (CTX-I) as markers of bone demineralization. At 40 weeks of age, three birds per pen (n = 84) were euthanized for computed tomography scans to obtain tibial bone mineral density (BMD) and cross-sectional area (CSA) with further analysis including muscle deposition, tibial breaking strength, and tibial ash percent. During week 24, hens from CP, EP, and LP pens had the highest overall activity compared to hens from NP pens (p < 0.05) with no differences between treatments for overall activity level during weeks 36 or 40 (p > 0.05). During weeks 24, 36, and 40, hens from CP and LP pens showed greater vertical and less horizontal activity compared to hens from EP and NP pens (p < 0.05). TRACP-5b and CTX-I concentrations did not differ between treatments at week 24 of age (p > 0.05). Hens from CP pens had the lowest TRACP-5b and CTX-I concentrations at 36 weeks of age with EP and LP hens showing intermediate responses and NP hens having the highest concentration (p < 0.05). At 40 weeks of age, CP hens had the lowest TRACP-5b and CTX-I concentrations compared to NP hens (p < 0.05). Total bone CSA did not differ between treatments (p > 0.05), but CP had greater total BMD than NP (p < 0.05) with no differences between EP and LP treatments. CP and LP hens had larger biceps brachii, pectoralis major, and leg muscle groups as well as greater tibial breaking strengths than EP and NP treatments (p < 0.05). CP hens had higher tibial ash percentages compared to EP, LP, and NP (p < 0.05). Our results indicate that providing continuous perch access improves the musculoskeletal health and activity of laying hens at 40 weeks of age compared to no access and that late access to perches has a beneficial impact on activity, muscle deposition, and bone strength.

Cat colonies and flight initiation distances of urban birds: Dealing with conflicting sources of citizen wellbeing

Feral cat colonies in cities improve the wellbeing of people who feed and care for them, but they can have negative effects on biodiversity due to the predatory behaviour of cats. We analyse the effect of the presence of the 1171 colonies of feral cats reported for the city of Madrid (Spain) on the flight escape distances (FIDs) of birds to approaching human observers under standardized conditions. Location of cat colonies was obtained from maps maintained by the city authorities. The FID is a behavioural trait that integrates effects on bird's fearfulness of exposure to predation, disturbance, and physiological and reproductive needs. Shorter flight distances are associated with less exposure to predators and disturbance and better access to food and mates. Shorter FIDs are also associated to higher abundances and more positive population trends, at least in Spain. Mean FIDs of 694 birds of 34 species measured in nine city areas in the spring of 2021 were 10% longer in zones with colonies of feral cats than in neighbouring paired zones without colonies but similar regarding other factors potentially affecting FIDs (i.e. urban landscape structure). Birds were 33% higher above ground in zones with colonies, with no significant effects of perching higher on bird fleeing behaviour. Cat colonies were therefore increasing the fearfulness of individual birds and, presumably, downgraded their population trends. Compromising bird conservation with wellness effects of cat colonies on citizens at the city scale will thus imply the maintenance of colony-free areas, especially for ground-foraging birds. In addition, provision of perches for its use as temporal refuges around colonies might reconcile positive and negative effects at local scales.

Conservation Letter: Raptors and Anticoagulant Rodenticides

Conservation Letter: Raptors and Anticoagulant Rodenticides

Functional consequences of flower curvature, orientation and perch position for nectar feeding by sunbirds

AbstractMutualisms between nectarivorous birds and the plants they pollinate are functionally diverse. Nectarivorous birds which hover while feeding (the majority of hummingbirds) tend to have straight bills, while those that perch while feeding (some hummingbirds and almost all passerine nectarivores) tend to have decurved bills. Sunbirds typically use their curved bills to feed in an arc from a perching position and we thus predicted that they would prefer, and feed most efficiently on, flowers that are curved towards a perching position. To test this, we examined the responses of sunbirds to model flowers differing in curvature (straight or curved), orientation (facing upwards or downwards), and availability of a top perch (present or absent). Birds did not show preferences among model flower types in terms of number of landings to feed or number of probes. In general they preferred to use perches above model flowers, particularly those that curved upwards, but they tended to perch below model flowers that curve downwards and in such cases also took the least time to insert their bills. These results are consistent with the idea that perching birds with curved beaks will feed most efficiently from flowers that are curved towards the perching position. We discuss the implications of these results for the evolution of floral architecture, including provision of perches.

Provision of perches and their use by broiler breeders on the basis of a case study

Introduction In Germany, approximately 3.4 million female broiler breeders are kept for hatching egg production to generate about 414 million broiler chickens per year (KTBL, 2008). Regarding perches, there are no specific legal regulations for

Improving leg health in broiler chickens: a systematic review of the effect of environmental enrichment

AbstractLeg problems are highly prevalent in modern broiler production and provision of environmental enrichment could be a strategy to improve leg health. Different types of environmental enrichment have undergone evaluation. Our objective was to conduct a systematic review of the effect of environmental enrichment on leg health in broiler chickens. The evaluation of leg health included measures of the entire leg and foot, and behavioural, pathological and physical measures. Six types of environmental enrichment were selected for inclusion: light programme, intensity of light, stocking density, perches, straw bales and separation of resources. For each type, a systematic literature search was performed. The review included 62 studies; 56 randomised trials and six cross-sectional studies. An assessment of the methodological quality of all 56 randomised trials was performed with some reporting deficits regarding occurrence of blinding, randomisation and reliability of measures. Provision of perches and increased intensity of light only displayed limited effectiveness in improving leg health and both mainly affected contact dermatitis. In contrast, there was evidence that a lowered stocking density and a dark/light schedule could improve leg health. Few studies have been carried out on the effect of straw bales and separation of resources. The few studies done have, however, shown that both types of enrichment can be effective in improving leg health. In conclusion, identifying and providing the optimal types of enrichment for broilers will reduce leg problems and increase mobility, thereby improving the welfare of the birds.

Effects of lighting, stocking density, and access to perches on leg health variables as welfare indicators in broiler chickens

An experiment was conducted to investigate the effects of lighting program, stocking density, and the provision of a perch on leg health variables as welfare indicators in broiler chickens. A total of 360 mixed sex Ross 308 1-D-old broiler chickens (180 male and 180 female) were placed in a completely randomized design with 2 × 2 × 2 factorial arrangement of lighting program (continuous or restricted), stocking density (12 or 18 birds/m2), and the provision of a perch (perch or without perch). At d 42, tibial dyschondroplasia (TD), valgus-varus deformity (VVD), footpad dermatitis (FPD), and hock burn (HB) were scored. In addition, tibio-tarsal index, robusticity index, bone weight-length index, tibia crude ash content, and fluctuating asymmetry (FA) and relative fluctuating asymmetry (rFA) of tibia width and length were measured. The incidence of TD increased in broiler chickens subjected to continuous lighting (P < 0.05) in comparison with those subjected to restricted lighting. Presence of a perch reduced the incidence and severity of FPD (P < 0.01) compared to without a perch. Restricted lighting tended (P = 0.093) to decrease the incidence and severity of HB lesions. The broiler chickens placed at low stocking density (12 birds/m2) and with access to a perch had lower incidence and severity of HB lesions (P < 0.01 and P < 0.001, respectively) compared to their corresponding opposite groups. Tibio-tarsal index was greater (P < 0.01) in broiler chickens subjected to restricted lighting regimen compared to continuous lighting whereas the provision of a perch tended to increase (P = 0.081) the tibio-tarsal index in broiler chickens compared to those without perch. There was a tendency of decreasing tibia crude ash content with increasing stocking density from 12 to 18 birds/m2 (P = 0.056). However, birds without perches had greater (P < 0.01) tibia crude ash content compared those with a perch provided. Continuous lighting increased the FA and rFA of tibia length in comparison with restricted lighting program (P < 0.05) in broiler chickens. In conclusion, it can be said that restricted lighting programs and provision of perches may help reduce the leg health problems thus contributing to improved welfare in broiler chickens.

Use of aerial perches and perches on aviary tiers by broiler breeders

Perching, especially during the night, is an innate behaviour of chickens and the provision of perches is mandatory for laying hens in multiple countries. We examined whether broiler breeders of the fast (Ross 308) and relatively slow (Sasso) growing hybrids used aerial perches (P) and perches on aviary tiers (A) during rearing and production and how it affected welfare and production in comparison to controls without perches. Two hybrids and three treatments (control, aviary, perch) were employed in a cross-factorial arrangement. Control pens consisted of litter, raised slats, group nests, two feeder and one drinker lines. Perch-pens (P) included eight wooden perches in an A-frame configuration at 25, 50, 75, 100 cm above the slats and aviary-pens (A) included four aviary tiers with wooden bars and perches arranged as a platform (70 × 450 cm) at 55, 68, 115, and 138 cm above the slats. Each treatment combination was replicated three times resulting in a total of 18 pens. Welfare parameters of hens were assessed at 45 weeks and production was monitored continuously. Both hybrids used perches increasingly with age and predominantly at night (both tests P < 0.0001). Birds in control pens perched on the grill above the feeders and drinking lines more than birds in A or P (P = 0.0002) and perches were more used in A than P pens (P = 0.002). More brood eggs were collected in control pens than in the other treatments (P = 0.02) and A-pens yielded more floor eggs (P = 0.007) than control pens and P-pens. Keel bone fractures were less frequent than in laying hens but hens in A and P pens had more keel bone fractures than hens in control pens (P = 0.02) and Sasso had more than Ross (P = 0.002). In conclusion, our results suggest that broiler breeders are highly motivated to access aerial perches or perches on aviary tiers similar to laying hens with a similar welfare problem of keel bone fractures. Perches had no influence on hatching rates but measures should be taken against floor eggs to avoid a loss of brood eggs.

Perch-shape preference and perching behaviors of young laying hens

Provision of perches in enriched colony or cage-free hen housing facilitates birds’ ability to express natural behaviors, thus enhancing animal welfare. Although considerable research has been conducted on poultry perches, further investigation is needed of perching behavior and preference of laying hens to perch exposure and perch types. This study aimed to assess preference of young laying hens for round vs. hexagon perches and to characterize temporal perching behaviors of the young hens brought to an enriched colony setting from a cage pullet-rearing environment. A total of 42 Lohmann white hens in six equal groups, 17 weeks of age at the onset of the experiment, were used in the study. Each group of hens was housed in a wire-mesh floor pen equipped with two 120 cm long perches (one round perch at 3.2 cm dia. and one hexagon perch at 3.1 cm circumscribed dia., placed 40 cm apart and 30 cm above the floor). Each group was monitored continuously for 9 weeks. Perching behaviors during the monitoring period, including perching time, perch visit, and perching bird number, were recorded and analyzed daily using an automated perching monitoring system. Results revealed that the laying hens showed no preference between the round and hexagon perches (P = 0.59–0.98). Young laying hens without prior perching experience showed increasing use of perches over time (P < 0.01). It took up to five to seven weeks of perch exposure for young hens to show consistent perching behaviors in the enriched colony setting. This study also found that laying hens spent about 10% of daytime on the perches and over 75% of hens perched at night after approaching consistent perching behaviors. In general, the results supplemented to the existing knowledge base for the quantitative behavior study on laying hens’ temporal perch use.

The effect of environmental provisioning on stress levels in captive green anole (Anolis carolinensis)

AbstractIn response to an increased awareness concerning the welfare of captive animals, several studies have investigated the effect of provisions on stress levels in model species, such as small mammals, birds and fish. In contrast, reptiles have received less attention. Although many reptilian species are becoming increasingly popular in the pet trade and are frequently used as model species in various branches of biology and a number of studies have explored how they react to stress in different contexts (eg social, predatory), little is known about how they react to stress induced by housing conditions or experimental treatments. In this study, we quantified the effect of provision of perches and leaves as refuges (provisioned) on the behaviour, morphology and physiology of the green anole (Anolis carolinensis). Our results showed that increased or decreased structural complexity of the cage had no effect on body mass, tail-base width, heterophil to lymphocyte ratios (H/L ratios), brightness, body colour, behaviour and faecal corticosterone metabolite (FCM) levels for both males and females in the experimental treatments (provisioned or deprived situation). Our study animals did score very highly for several stress-indicating variables in the three weeks preceding the experiments — suggesting that they had experienced considerable stress during capture, transport and temporary housing in the pet store.

Behavior as welfare indicator for the rearing of broilers in an enriched husbandry environment—A field study

In modern meat production, broiler chickens are usually barn raised in deep litter where a special structured environment is typically not intended. Natural behaviors of the domestic fowl, such as running freely, pecking, scratching, flapping wings, grooming plumage, resting and sleeping undisturbed, can be restricted by lack of opportunities. Additional welfare concerns in industrial poultry farming are high stocking densities and genetic traits. Consumer surveys show an increasing public awareness of problems in livestock farming and the willingness to make a difference by spending more money on food coming from animal-friendly production. For this segment, the market offers organically produced products at higher costs, whereas the possibility for an intermediate product that meets animal welfare, consumer requirements, and economic aspects has barely been used. By increasing the environmental complexity with the provision of perches (15.9 m per 1000 birds), straw bales (1.7 per 1000 birds), pecking stones (1.1 per 1000 birds) and access to a roofed outside run (624 m2) and by using a reduced stocking density (16 birds per m2) and selecting Cobb Sasso 175 as a slower-growing broiler strain, we intended to improve bird welfare. We therefore established, tested, and scientifically evaluated an alternative rearing concept for broiler chickens on its way to market suitability. In addition, a conventional farm with Ross 308 broilers reared at a stocking density of 23 birds per m2 was evaluated for comparison. The study included 6 rearing periods per concept and an additional 2 rearing periods with the broiler strain Ross 308 under the alternative concept. For the behavioral observations, video recordings were carried out simultaneously in both barns during all rearing periods in a weekly 24-hour interval. Results show that Cobb Sasso broilers reared with the alternative concept were more active during the observation intervals than conventionally reared Ross 308 broilers. The provided enrichment was well accepted and used. The straw bales were used as shelter for resting behavior during the early rearing phase and later as pecking objects and elevated resting areas. Perches were used as of day 9. The provision of environmental enrichment in broiler rearing can stimulate species-specific behaviors and therefore can increase animal welfare while meeting consumer requirements in an economic way.

Effect of perches on liver health of hens

Fatty liver is a common energy metabolic disorder in caged laying hens. Considering that the egg industry is shifting from conventional cages to alternative housing systems such as enriched cages, the objective of this study was to determine the effects of perches on fat deposition and liver health in laying hens. Three hundred twenty-four 17-wk-old White Leghorn hens were housed in 1 of 4 treatments with 9 hens per cage. Treatment 1 hens never had access to perches during their life cycle. Treatment 2 hens had access to perches during the pullet phase only. Treatment 3 hens had access to perches during the laying phase only. Treatment 4 hens always had access to perches. Liver weight, abdominal fat pad weight, BW, liver fat, and circulating alanine transaminase, aspartate transaminase, and adiponectin were determined. Provision of perches during either the rearing or laying phase did not affect liver health in 71-wk-old hens. However, perch access compared with no perch access during the egg laying phase reduced relative fat pad weight. These results suggest that providing perches as a means of stimulating activity reduced abdominal fat deposition in caged hens during the laying period. However, perch access in caged hens was ineffective in reducing fat deposition in the liver and altering enzyme activities related to improved liver function.

Choice of perch characteristics by laying hens in cages with different group size and perching behaviours

Provision of perches in cages could improve behaviour and physical conditions of laying hens. This study was conducted to investigate the choice of perch characteristics (shape, width, material and height) by caged hens under different group size, and to understand the choice by the perching behaviours of hens. This study was consisted of four trials: perch shape (rectangular and round in cross section), width (3.0cm and 5.0cm), material (steel, wood and plastic) and height (10cm, 20cm, 30cm and 40cm) tests. In each trial, 390 Hyline Brown laying hens were used and randomly allocated to three treatments: individual group (G1), group of four hens (G4), and group of eight hens (G8), respectively. There were 30 replicates in each group. The hens in G1, G4 and G8 groups were put in the test cages in which designed perches were simultaneously provided and tested after four habituating days. Hens’ behaviours were recorded using cameras at the following periods: 8:00–10:00; 14:00–16:00; 19:00–21:00 and 23:30–0:30 on the fifth and seventh day. The behaviours of the hens were analyzed, and the hens’ positions on test perches during mid-night were recorded. The results showed that, the rectangular perches were chosen more than round perches in all groups (p<0.01), and comforting behaviour was performed more (p<0.05) on the rectangular perches than on the round ones. The 3.0cm wide perches were highly preferred to 5.0cm perches in G1 and G4 groups (p<0.05). The hens on the 5.0cm wide perches performed more pecking (p<0.01). Besides, the wood perches were chosen more than steel or plastic perches in all groups (p<0.05). The hens chose 20cm high perches most in G1 group and G4 groups (p<0.05), but 10cm high most in G8 groups (p<0.01). The perching behaviour was significantly affected by perch height (p<0.05). Besides, the frequency of jumping, pecking and comforting were significantly affected by group size (p<0.05). Consequently, we recommend that the rectangular wood perches of 3.0cm wide and 20cm high may be suitable for the commercial furnished cages that the height is not lower than 100cm.

Pressure load on keel bone and foot pads in perching laying hens in relation to perch design

The provision of perches in housing systems for laying hens is meant to improve hens’ welfare by allowing a more natural behavior repertoire. However, the use of perches is associated with welfare problems, such as keel bone deviations and foot pad lesions, that may possibly result from high mechanical pressure load during extended perching activities. The aim of this study was to analyze peak force and contact area of hens’ keel bones and foot pads on solid test perches of square, round, and oval shape with 3 different diameters each (experiment 1) and on commercially used perches (round steel tube, 2 sizes of mushroom-shaped plastic, and flattened round plastic) together with 2 prototypes of soft, round polyurethane perches (experiment 2). Test perches were covered with a pressure sensor film and 36 laying hens (18 Lohmann Selected Leghorn, 18 Lohmann Brown) were consecutively placed on each perch in an experimental cage during nighttime. Peak force (N/cm2) and contact area (cm2) were measured while hens were sitting and standing on the different test perches. Pressure peaks on the keel bone were approximately 5 times higher compared with single foot pad. On square perches, keel bone peak force was lower (P < 0.05) and contact area was larger (P < 0.001) compared with round and oval perches. In addition, peak force on foot pads in standing hens was higher on square perches (P < 0.05) compared with oval perches. Perch size did not affect peak forces on keel bones in sitting hens and foot pads in standing hens (experiment 1). On prototype perches, peak force on the keel bone was lower and contact area was larger compared with all commercial perches tested (P < 0.001). Peak force on foot pads was lower on prototype perches compared with steel perches (P < 0.01; experiment 2). Perches with a soft surface may possibly reduce keel bone and foot pad welfare problems in perching laying hens.

Strengthening US organic standards on animal health and welfare

AbstractOrganic livestock production has been increasing in the US, although it still merely constitutes a small fraction of total production. Its success will require detailed standards supported by scientific knowledge and consistent with organic farming principles. However, such standards, mandated under the Organic Foods Production Act of 1990, are yet to be fully developed. Regulations issued by the USDA's National Organic Program identify livestock health and welfare concerns that must be addressed in a farmer's organic farm plan (eg that there be appropriate housing). However, specifics regarding achievement of these goals are not provided in the form of clear standards for organic livestock production. This paper provides a new starting point to further the development of such standards. First, we outline a rationale based upon the legal context and state of the organic livestock industry detailing the reasons why development of these standards is timely. Second, using a review of existing organic and nonorganic national and international animal health and welfare standards, a search of available scientific research, and a consensus of key stakeholders, we identify areas in which organic standards should be readily adopted. We conclude by presenting one example of a plausible organic standard for each of four major US livestock categories: minimum space for feedlot beef cattle; prohibition of routine tail-docking in dairy cows; provision of perches for laying hens and prohibition of gestation crates for sows.

Effect of Improved Housing Design and Sexing on Carcass Traits and Fatty Acid Composition of Meat in Broiler Chicken

Simsek, U.G., Ciftci, M., Cerci, I.H., Gurses, M. and Guvenc, M. 2009. Effect of improved housing design and sexing on carcass traits and fatty acid composition of meat in broiler chicken. J. Appl. Anim. Res., 36: 219–222. To study the effects of improved housing design (sand bedding and provision of perches) and sexing on carcass traits and fatty acid composition, 480 Ross-308 chicks were assigned to two groups including equal number of male and female. At d 42, 8 representative males and 8 females were slaughtered from each group. Their carcasses were evaluated. Fatty acid composition of whole carcass (4 males, 4 females) and meat from breast and left thigh from the remaining 4 males and 4 females were evaluated. Carcass traits did not differ between groups. Total PUFA, ω-3 and ω-6 ratios increased and total SFA and MUFA ratios decreased (P<0.001), in the improved housing group. Total SFA was found to be higher in female than male broiler (P<0.05). It was concluded that improved housing with perches and sand bedding improved chicken meat quality and increased total polyunsaturated fatty acid ratio of the meat. Sexing significantly affected fatty acids composition of meat.

Keel bone condition in laying hens: a histological evaluation of macroscopically assessed keel bones.

The objective of the present study was to conduct a corresponding histological analysis of 162 macroscopically assessed keel bones (1: severe, 2: moderate, 3: slight, 4: no deformity). Four layer lines were used and hens were kept in furnished cages, small group systems (both allowing more activities due to the provision of perches) and an aviary system, which fully conformed to the EU standards. Investigations were carried out in the 3rd, 6th, 9th and 12th laying month of two experimental trials. In 97.9% of grade 4 keel bones, no histological deviations were found, whereas in keel bones manifesting deformities of grade 1 and 2, the predominant histological observation was the incidence of fracture callus material (FCM) and new bone in the form of woven bone. FCM was also detected in 50.9% of grade 3 keel bones, whereas in 40.7%, only s-shaped deviations of keel bones were found, which were related to extended pressure loading while perching activities rather than short-duration trauma. Histological analysis showed that keel bones of grade 1 and 2 were mainly attributed to traumatic origin and therefore associated with pain experience in layers. Grade 3 keel bones manifested either FCM as a result of trauma or adaptational deformities without any evidence of a preceding fracture in response to mechanical pressure loading and were most likely not associated with pain. Therefore, histological analysis was found to be a mandatory tool when evaluating grade 3 keel bones with respect to layers'welfare. Furthermore, this analysis corroborates the findings that in aviary systems deformities of keel bones are predominantly caused by painful fractures.

Use of perches and nestboxes by laying hens in relation to social status, based on examination of consistency of ranking orders and frequency of interaction

Four groups of 15–19 adult ISA Brown hens were studied in pens to assess the relationship between social status and use of perches and nestboxes. This was to test the hypothesis that subordinate hens use these resources more by day, for avoiding dominants, but that dominants use perches more at night, for roosting. The experiment consisted of a 5-week pre-treatment period, when no perches were present, and a 4-week treatment period, when each group was tested with different perch treatments (No, Low, Medium, High). All groups were observed systematically in each week, when all interactions of three types (aggressive peck, non-aggressive peck, approach/avoidance) in a group were recorded by noting the instigator and recipient (from numbered wing tags) onto a matrix. Proportions of time that each bird spent using perches and nestboxes, by day and at night, were also recorded. The results indicate that social status of individual laying hens is relatively stable across time and can be based reliably on counts of either aggressive pecks or approach/avoidances, but not non-aggressive pecks. Aggressive pecks were the most frequent type of interaction observed, and were reduced by the presence of perches. Use of nestboxes, but not perches, was greater at night than by day. There were weak tendencies for perches, and to a lesser extent nestboxes, to be used more by lower ranking birds by day, but not at night. There was some evidence of increased use of these resources by higher ranking birds at night. It is concluded that provision of perches reduces bird density on the floor (where nearly all interactions occurred), allows subordinates a means of avoiding dominants by day, reduces frequency of agonistic interactions, and should thus benefit laying hen welfare.

Perch length in cages for medium hybrid laying hens.

1. ISA Brown hens were housed as groups of 4 from 18 to 72 weeks in 24 cages 450 mm deep, each with a softwood perch of rectangular cross-section fitted across the rear. There were 4 treatments, each with 6 cages: cage widths and perch lengths were 480, 520, 560 or 600 mm. 2. Daytime perching did not differ significantly between the treatments. At night, over the whole year, 81% of birds in the 480 mm cages and 86% in the 520 mm cages roosted on the perch. This figure reached about 95% in the 560 and 600 mm cages, significantly more at most ages than in the 480 mm cages. 3. Feather damage was slightly less, but claw problems slightly more, in the 2 wider treatments than in the 2 narrower treatments. Birds in the wider cages were calmer when approached or handled by humans than those in the narrower cages. This may have been associated with variation in space allowance between the treatments. 4. There was a trend for lower production in the 480 mm cages than in the other treatments which may have been associated with the reduced feeding space in this treatment. There were few other treatment differences in production traits. 5. The balance of the evidence from this study is that when perches are provided in laying cages for medium weight hybrids, 140 mm of perch space per hen is adequate. For the amelioration of a number of the welfare problems of conventional cages, provision of perches should be combined with other modifications.

Effect of Age and Presence of Perches During Rearing on Tonic Immobility Fear Reactions of Broiler Breeder Pullets

Broiler breeders were housed in pens in an all-litter house with an 8-h photoperiod from hatching to 20 wk of age. They were reared either in the presence or absence of perches (7 cm per bird) and on either a 14% or a 17% CP diet. The duration of the tonic immobility (TI) fear response was measured in 15- and in 20-wk-old birds; each pullet was tested individually and once only. There was an apparent age-related increase in the duration of TI, which was attenuated by the provision of perches during rearing. The results are discussed in terms of maturational and environmental influences on the development and alleviation of fear.